Heat the oven to 350 degrees F. Lightly coat 2 muffin tins with cooking spray. In a mixing bowl, combine the pumpkin puree, yogurt, eggs, oil and vanilla. In a medium bowl, combine the flour, sugar, cinnamon, baking soda, cloves and salt. Slowly combine the dry ingredients into the bowl with the wet ingredients, using a mixer. Mix ingredients until just incorporated, about 1 to 2 minutes. Scoop 1/4 cup batter into each muffin well. Bake for 25 to 30 minutes or until muffins spring back when pressed lightly on top and a toothpick comes out clean when inserted.