window = first 100 rows without missing values
 default 0.5
 ColumnDriftMetric(stattest_threshold=0.3) on three columns -> 0.5 True
 DatasetDriftMetric(per_column_stattest_threshold) -> 0.125 False
 DatasetDriftMetric(drift_share=0.7) -> 0.5 False
 DatasetDriftMetric(stattest='chisquare') -> 0.125 False

no shift, dataset drift rate with the library, 300 windows
    n  full reference, chisquare  1000-row reference, default
   50                       0.7%                         1.7%
  100                       0.7%                         5.7%
  200                       0.0%                         9.0%

Native_country categories 42 below 1%: 39