teffects overlap 这个图（见附件）是不是只能在stata13.0里实现啊，stata12.0可以实现吗?stata12.0有overlap命令，不过结果如下这样的，如何解释啊?
overlap age,by (private)
MLE of overlap:
  Variances equal:   0.9680     Dissimilarity Index=1-OVL: 0.0320
  Variances UNequal: 0.6427     Dissimilarity Index=1-OVL: 0.3573


. overlap  edu13,by (private)
MLE of overlap:
  Variances equal:   0.7125     Dissimilarity Index=1-OVL: 0.2875
  Variances UNequal: 0.8602     Dissimilarity Index=1-OVL: 0.1398