When sunspot numbers are high, how is propagation affected?

Sunspots are regions of intense magnetic activity on the sun that strongly correlate with higher emissions of ultraviolet and X-ray radiation. When sunspot numbers are high, the Earth's ionosphere becomes much more highly ionized, which significantly increases the Maximum Usable Frequency (MUF). During these peaks of the solar cycle, the F-layer becomes dense enough to refract much higher frequencies back to Earth. This allows frequencies up to 40 MHz, and occasionally even up to 50 MHz (the 6-meter band), to become reliable for long-distance (DX) communication. Distractors suggesting absorption or distortion confuse the positive effects of high sunspot numbers with the negative effects of sudden solar flares, while 100 MHz is generally too high and will pass through the ionosphere regardless of the cycle.