WASHINGTON (AP) — Booming online retail sales are good news for the U.S. Postal Service, but its carriers are incurring a cost: more dog bites.

Dog attacks on postal workers rose last year to 6,755, up 206 from the previous year and the highest in three decades. The popularity of Amazon and other internet retailers is changing consumer habits, from seven-day-a-week delivery to groceries at your doorstep. The high for attacks dated back to the 1980s, before maulings by pit bulls and other potentially aggressive dogs became a public issue.

Los Angeles topped the list in 2016 with 80 attacks. It was followed by Houston with 62 and Cleveland with 60.

The Postal Service released figures Thursday as part of National Dog Bite Prevention Week, which begins Sunday.