我有一个如下数据框:
year income group
1 2008 27907 Under25
2 2009 25522 Under25
3 2010 26777 Under25
4 2008 58809 Age25_34
5 2009 57239 Age25_34
6 2010 58558 Age25_34
7 2008 75677 Age35_44
8 2009 74900 Age35_44
9 2010 74136 Age35_44
10 2008 78537 Age45_54
11 2009 77460 Age45_54
12 2010 76266 Age45_54
13 2008 69009 Age55_64
14 2009 67586 Age55_64
15 2008 44402 Age65_74
16 2009 46147 Age65_74
17 2010 48595 Age65_74
18 2008 32747 Over75
19 2009 31272 Over75 …r ×1