There are a total of 183 living cardinals, with 112 of those under the age of 80 and thus able to vote in a conclave were it to become necessary.
Only 30 of those 112 were created cardinals by Pope Benedict XVI, all of the remaining cardinal electors were created by Pope John Paul II.
Eleven cardinals will lose their vote this year as they reach 80 - all were created by Pope John Paul II.
Nine more cardinals will lose their vote next year for the same reason. But two of those were created by Pope Benedict XVI.
Thirteen more lose their vote in 2012. Two of this group were created by Pope Benedict XVI.
The following table is for Cardinal Electors only.
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Here are a couple of links that might be useful for further research: Cardinal Electors by Age and Cardinals by Rank.
Note: all of the above figures assume no Cardinal dies before reaching the age of 80 and obviously don't include any new Cardinals created.