Because the statistics are based on the nationality of company/agency that designs and builds the launch vehicle, not the launch site. So even though Soyuz launches from Kazakhstan and French Guiana, it is counted as a Russian launch since a Russian company (Energia) designed and built the rocket. Similarly, even though a lot of Electron launches are from New Zealand, the company that builds Electron is ultimately US-headquartered/US-controlled. (Rocket Lab was originally founded in New Zealand, but they moved their HQ and parent company to the US so are now considered a US company rather than a New Zealand one.)