year,a,na
1997,354463148,245801173
1998,292306804,257599552
1999,227432998,593504535
2000,247909122,522187695
2001,241757314,526015959
2002,202678682,571461611
2003,323040758,612368899
2004,213053902,554871881
2005,181130450,730519666
2006,138932208,623337539
2007,109721758,711193371
2008,98128017,754482768
2009,84249270,746871345
2010,107100969,826677151
2011,104459713,738442581
2012,92577343,821899877
2013,75417807,779449577
2014,64367287,823735102