Over the first two decades of settlement Aboriginal people launched at least 57 attacks on white settlers, punctuating a general calm,[23] but by 1820 the violence was becoming markedly more frequent, with one Russian explorer reporting that year that "the natives of Tasmania live in a state of perpetual hostility against the Europeans".[24] From the mid 1820s, the number of attacks initiated by both whites and blacks rose sharply. Clements says the main reasons for settler attacks on Aboriginal people were revenge, killing for sport, sexual desire for women and children and suppression of the native threat. Van Diemen's Land had an enormous gender imbalance, with male colonists outnumbering females six to one in 1822 and the ratio as high as 16 to one among the convict population.