Year,Avg_num_tow_female,Avg_num_tow_male
1981,0.7217,0.6211
1982,0.6989,0.5273
1983,0.6226,0.7196
1984,0.6162,0.5754
1985,0.5605,0.4972
1986,0.9691,0.8228
1987,0.6678,0.7490
1988,0.7258,0.7871
1989,0.6584,0.8711
1990,0.7041,0.5847
1991,0.8402,0.5118
1992,0.8836,0.4920
1993,0.6743,0.3525
1994,0.5674,0.5387
1995,0.6269,0.3176
1996,0.5612,0.3932
1997,0.8490,0.7768
1998,0.7317,0.5477
1999,0.8203,0.6654
2000,0.7766,0.6746
2001,1.1147,0.4641
2002,1.5099,0.9770
2003,0.8455,0.5988
2004,0.8920,0.2908
2005,0.8672,0.2387
2006,1.0423,0.2285