one-and-half year vs one-and-a-half-year

Some examples from the web:

• Mr Verheugen said he was not aware of delays, but stressed that the problems with Polish agricultural administration had been known for one and half years.
• Mr Verheugen said he was not aware of delays, but stressed that the problems with Polish agricultural administration had been known for one and half years.
• The interval between examinations ranges from one and half to three years.
• And we all share this incredible heritage of having originally been darkly pigmented, two million to one and half million years ago.
• Since its inception it was not convened until the present Government came to power, one and a half years ago.
• The Commission proposed Agenda 2000 one and a half years ago.
• Member States will have one and a half years to put most of the new rules into effect.
• One person got a suspended sentence of one and a half years.
• The world has one and a half years to change course before Copenhagen.
• One and a half years without a clue.
• I say 'finally' because Parliament had waited for more than one and a half years.
• Mr President, the Commission communication which we are discussing was published one and a half years ago following the outbreak of war in Central Africa.
• General failure, due to the effect of the cancer over the last one and a half years.
• The first wave of enlargement must be completed in one and a half year's time in Copenhagen in December 2002.
• Approximately one and a half years ago, three Israeli soldiers were abducted in Gaza.
• Unfortunately, even one and a half years on, there is still an alarming gap between the rhetoric and the reality of the Prodi Commission.
• This is our one and a half years ago related to the attack.
• It is fair to say that after one and a half years of negotiations, we are approaching the most intensive phase.
• The case of Irina Petrushova with Respublika weekly, sentenced to one and a half years in jail is another example.
• Parliament decided on this one and a half years ago, but until today the Council has had nothing to say on the subject.

Some examples from the web:

• Since its inception it was not convened until the present Government came to power, one and a half years ago.
• The Commission proposed Agenda 2000 one and a half years ago.
• Member States will have one and a half years to put most of the new rules into effect.
• One person got a suspended sentence of one and a half years.
• The world has one and a half years to change course before Copenhagen.
• One and a half years without a clue.
• I say 'finally' because Parliament had waited for more than one and a half years.
• Mr President, the Commission communication which we are discussing was published one and a half years ago following the outbreak of war in Central Africa.
• General failure, due to the effect of the cancer over the last one and a half years.
• The first wave of enlargement must be completed in one and a half year's time in Copenhagen in December 2002.
• Approximately one and a half years ago, three Israeli soldiers were abducted in Gaza.
• Unfortunately, even one and a half years on, there is still an alarming gap between the rhetoric and the reality of the Prodi Commission.
• This is our one and a half years ago related to the attack.
• It is fair to say that after one and a half years of negotiations, we are approaching the most intensive phase.
• The case of Irina Petrushova with Respublika weekly, sentenced to one and a half years in jail is another example.
• Parliament decided on this one and a half years ago, but until today the Council has had nothing to say on the subject.
• I remember talking about this for the first time in Australia, about one and a half years ago, when their academy honored me with a fellowship.
• One and a half years and 3,200 miles later, I am in Cape Town.
• For one and a half years, we have been looking on while two utterly unequal opponents wage war on each other.
• The report shows that much is left to be desired in terms of practical application one and a half years after the Community framework strategy for equality between men and women came into effect.