Chief executives for the Boston-area's largest hospitals mostly earned pay packages between $1 million and $3 million in 2010, and several received bonuses for attracting more patients, improving care, or simply by agreeing to take the job. Several large academic medical centers changed leaders during 2010, making it difficult to compare salaries from prior years. In at least two cases—Boston Children's Hospital and Tufts Medical Center—hospitals awarded their top executives sizeable increases. Nonprofit hospitals were required to report their 2010 financial information, including executive salaries, to Attorney General Martha Coakley's office on Wednesday.