Violent crime so far this year in the District has spiked sharply — a 40 percent increase that includes twice as many robberies at gunpoint than at this time last year. Across the city, all police districts are reporting increases in violent crime, and all but one have had double-digit percentage increases, according to internal Metropolitan Police Department documents. The documents contained preliminary crime data for the city as of Thursday. The crime rate is increasing this year after a downward trend — the number of reported homicides last year dropped to the lowest level in a half-century. Homicides were...