环比 同比
环比 与前期相比 SPLY (Same Period Last Year)
同比 与去年同期相比 LP (Last Period)
compare with the performance/figure/statistics last year, year-on-year ratio
increase/decrease on a year-on-year basis
环比则只需把前面的year改为month或season即可
定基比 Fixed base ratio 报告期水平与某一固定时期水平之比，表明这种现象在较长时期内总的发展速度 总速度
