More U.S. tourists are headed to Europe this year. With the U.S. dollar hitting a 12-year high versus the euro, overseas travel is far cheaper than it has been in years.

The European Travel Commission (ETC), which represents tourism boards in 33 countries, is expecting a 6.7 percent increase in the number of U.S. visitors in 2015. Between 2014 and 2019, growth is expected to average 5.3 percent. About 23.4 million Americans traveled to Europe in 2014, according to the ETC. Overall, data from the U.S. Commerce Department shows more than 68 million went abroad last year, a record. This was the first increase of more than 10 percent in a decade.

Airfares to some top destinations in Southern Europe, such as Italy and Spain, have plunged 21 percent in the first two months this year, 13 percent when taxes and fees are included, according to Priceline Group's (PCLN) priceline.com service. As a result, ticket sales to these markets have jumped 33 percent, the online travel giant said.

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"Regarding travel periods, these aggressive discounts have caused customers to snap up great deals early, with advance purchases increasing 9 percent vs. last year," Priceline said in a statement to CBS MoneyWatch. "The average ticket bought this year is in excess of three months prior to travel (94 days in advance), more than a week earlier than at this period last year. Peak travel months of May, June and July are each up over 17 percent in tickets vs. last year."

France, Italy, Ireland and the U.K. are among the countries expecting more U.S. tourists. According to data from the U.S. Department of Commerce, about 12 million Americans traveled to Europe last year. Air France-KLM has seen a 17 percent increase in American bookings for the summer season on both the Air France and KLM networks, according to Anne-Laure Tunce, the U.S. Director for ATOUT FRANCE-France Tourism Development Agency.

"The tour operators Avanti, Europe Express and Eurobound are all reporting an increase in bookings since the beginning of this month after a slowdown in February," she wrote. "The customers are all taking advantage of the exchange rate by upgrading hotels and booking more sightseeing tours. Avanti sees also an increase of bookings outside of Paris."

Italy was already expecting plenty of tourists this year because of Expo Milan, a five-month-long international showcase regarding environmental sustainability that begins in May. The weak euro will further encourage U.S. visitors, who are expected to increase by at least 10 percent this year, according to Marzia Bortolin, a spokeswoman for the Italian Government Tourism Board.

Tourism Ireland, that country's tourism office, saw gains of 13 percent and 14 percent in 2013 and 2014, respectively, in U.S. visitors and is targeting a 6 percent increase in 2015, said Allison Metcalfe, head of North American operations at Tourism Ireland. This year is shaping to be a banner year for Irish tourism: More than 7 million visitors are expected in the Emerald Isle, spending about $5 billion.

Record numbers of American tourists visited the U.K. in 2014, and officials there "remain really positive that 2015 is off to a really good start," said Karen Clarkson, Visit Britain's vice president for North America in an interview.