(Adds table, details, analyst comment, bitcoin futures) NEW YORK, April 26 (Reuters) – Speculators increased their net long U.S. dollar bets in the latest week to the highest level since December 2015, according to calculations by Reuters and U.S. Commodity Futures Trading Commission data released on Friday. The value of the net long dollar position was $37.21 billion in the week ended April 23, compared with $34.55 billion the previous week. U.S. net long dollars rose for a fourth straight week. U.S. dollar positioning was derived from net contracts of International Monetary Market speculators in the Japanese yen, euro, British pound, Swiss franc and Canadian and Australian dollars. In a broader measure of dollar positioning that includes net contracts on the New Zealand dollar,