年份,年平均(%)
1997,50.18
2008,43.36
2009,35.23
2010,28.7
2011,32.88
2012,35.84
2013,40.44
2014,41.81
2015,23.37
2006,44.87
2007,32.63
2008,37.68
2009,31.59
2010,35.18
2011,42.45
2012,37.28
2013,44.11
2014,41.19
2015,46.3
2016,39.38
2017,36.78
2018,40.37
2019,36.8