How to pronounce “nikkei 225” in English

Leeson's plan to recover his team's loss was to bet that the Japanese stock market would go up, so he went long on the top 225 companies in Japan,the Nikkei 225. Ever since the Japanese asset price bubble peaked two years previously, the Nikkei had been dropping from 38,000 to 16,000,and he was confident the market would soon bottom out and start rising, but it continued to fall.