National data on police shootings of the mentally ill are all but nonexistent, yet there are some statistics that help to inform the issue:

• The latest Police-Public Contact Survey by the U.S. Department of Justice, released last year, found that police used or threatened to use force against an estimated 1.9 percent of the 40 million people who had face-to-face encounters with officers in 2008.

That’s about 776,000 Americans who were shouted at, pushed, grabbed, tackled, pepper-sprayed, Tasered, held at gunpoint or worse. Among those who described their most recent encounter with police, 74 percent said the force was excessive and 19 percent said they were injured. Forty percent said they were arrested and 28 percent admitted they insulted, assaulted or otherwise interfered with the officers.

• Police function in a landscape where one in four American adults has a mental health disorder, according to the National Institute of Mental Health, at a time when more than $4.53 billion has been cut from state public mental-health budgets since 2009, according to the National Association of State Mental Health Program Directors.

In a time of rising need, the nation’s public mental health-care delivery system has been nearly level-funded at about $37 billion for the last four years.

During that period, use of public mental-health services has increased nearly 10 percent, the association reported. The number of people receiving state-funded, community-based mental health services has shown a similar increase, from 5.5 million in 2007 to 6.5 million in 2010.

• Despite growing need, states have greatly reduced public psychiatric hospital beds in the wake of deinstitutionalization that started in the 1970s, contributing to an increase in the percentage of prison inmates with serious mental illness, according to the Treatment Advocacy Center.

By 2010, there were 14 public psychiatric hospital beds per 100,000 of U.S. population, far below the 50 beds recommended to provide adequate mental health care, and reminiscent of numbers when so-called insane asylums opened in the 1840s. Recent studies show 17 percent to 60 percent of jail and prison inmates have a serious mental illness, up from 6 percent to 11 percent in the 1980s and 1990s.

As a result, the advocacy center reports, there are three times more mentally ill people in U.S. jails and prisons than in state psychiatric hospitals.

• Anecdotally, police across the nation report that people with mental health issues make up 5 percent to 20 percent of their calls. Some report recent increases of 50 percent or more.

• In Portland, Maine, Police Chief Michael Sauschuck has taken steps to improve data gathering on mental health-related calls, which almost quadrupled the annual tally from 856 calls in 2010 to 3,311 calls in 2011 – nearly 4 percent of calls for service that year.