contratista	periodo	tipo_alta	tipo_baja	fecha_afectacion
910	201605			
910	201606			
911	201605			
911	201606			
1312	201612			2017-01-12 11:16:03.003000000
1312	201701			2017-01-12 11:16:03.017000000
1313	201612			2017-01-12 11:16:22.030000000
1313	201701			2017-01-12 11:16:22.033000000
1369	201612			2017-01-24 15:31:51.017000000
1369	201701			2017-01-24 15:31:51.020000000
1370	201612			2017-01-24 15:31:23.100000000
1370	201701			2017-01-24 15:31:23.100000000
1371	201612			2017-01-24 15:31:33.270000000
1371	201701			2017-01-24 15:31:33.277000000
1372	201612			2017-01-24 15:31:41.883000000
1372	201701			2017-01-24 15:31:41.887000000
1373	201612			2017-01-24 15:31:13.570000000
1373	201701			2017-01-24 15:31:13.577000000
1391	201701	2		2017-02-06 17:48:31.953000000
1391	201702			2017-02-06 17:48:31.957000000
1392	201701	2		2017-02-06 17:48:25.750000000
1392	201702			2017-02-06 17:48:25.753000000
1393	201701	2		2017-02-06 17:48:39.523000000
1393	201702			2017-02-06 17:48:39.523000000
1419	201701	2		2017-02-07 11:42:02.700000000
1419	201702			2017-02-07 11:42:02.707000000