(CNN) Planned Parenthood is in the spotlight as Republicans push to block funding for the group because it provides abortions for women.

"We don't want to commit taxpayer funding for abortion, and Planned Parenthood is the largest abortion provider," House Speaker Paul Ryan said during a CNN town hall this month.

He said Republicans would rather shift those dollars -- and redirect Planned Parenthood's patients using those dollars -- to federal community health centers.

"You don't have these controversies by funding health centers," he said.

The vast majority of federal money that Planned Parenthood does receive goes toward preventive health care, birth control, pregnancy tests and other women's health services. The group turned 100 in October.

President-elect Donald Trump has expressed mixed views about the group, praising its "very good work for millions of women" while maintaining his promise to cut off federal funding if it continues to offer abortion services. None of the funding Planned Parenthood receives can legally be spent on abortion services.

What is Planned Parenthood, and what services does it provide? Here's the breakdown:

What is Planned Parenthood?

Planned Parenthood claims to be the largest provider of reproductive health services in the United States, offering sexual and reproductive health care, education and outreach to nearly 5 million women, men and adolescents annually worldwide.

It has 650 affiliate health centers across the nation, including standalone clinics and satellite offices. The services offered at different centers vary. It estimates that 2.5 million women and men in the US visit its affiliate health centers for services and information each year, and its website receives 60 million visits annually.

Of its patients, 83% were 20 or older, according to a Government Accountability Office report released in March 2015 (PDF) that looked at data from 2010 to 2012. Nearly 80% had incomes at or below 150% of the federal poverty level, according to the report.

With a focus on prevention, Planned Parenthood said that 80% of its patients receive services to prevent unintended pregnancy.

What services does Planned Parenthood offer?

This is how its services break down:

Abortion

Planned Parenthood says 3% of the services it provides are abortions.

323,999 abortions were performed in 2014, according to the organization.

Sexual education

Planned Parenthood says it provides sex education to 1.5 million young people and adults each year.

Pregnancy prevention and birth control

Planned Parenthood says it prevents an estimated 579,000 unintended pregnancies per year.

Contraception accounted for 34% of the services it provided, according to the 2015 GAO report.

In 2014, Planned Parenthood saw:

2 milion reversible contraception patients

941,589 emergency contraception kits

3,445 vasectomies

718 female sterilization procedures

Pregnancy tests: 1.1 million tests done in 2014

Prenatal care: provided to 17,419 people in 2014

Sexually transmitted disease screening and treatment

Planned Parenthood says this accounts for 42% of the services provided. (The GAO calculates 41% in 2012 by affiliates.)

4.2 million tests and treatments provided in 2014

This represents the largest proportion of medical services provided.

Pap smears (cervical cancer screening): 270,000 per year

Breast exams: 360,000 per year

Research: Planned Parenthood said in its 2013-14 annual report that it participated in more than 70 research projects.

According to the Guttmacher Institute (PDF), publicly funded family planning in 2014 helped women avoid 2 million unintended pregnancies.

It found that 62% of Planned Parenthood health centers also offer same-day appointments, and 78% offer extended evening or weekend hours for those who have a hard time accessing care due to work or family responsibilities. Planned Parenthood is also more likely to facilitate the choice and uptake of a contraceptive method, as well as help a high volume of patients who need contraceptive care.

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Guttmacher also says that Planned Parenthood health centers serve 36% of all clients obtaining care from publicly funded family planning centers and that in 2014, 20.2 million women in the US were in need of publicly funded family planning services like Planned Parenthood.

According to a 2016 survey, 26% of patients at a Planned Parenthood site said it was the only place they could go for the services they required.

The Guttmacher Institute identifies itself as a nonprofit that works to advance sexual and reproductive health worldwide through research, policy analysis and public education.