Because it's a little hard to see, the first screenshot is of one of my crit Healing Waves, which landed on a warlock for 9895. Almost 10,000 health in one shot.
The second screenshot is of our last raid where we spent 4 hours wiping 19 times on the Illidari Council. It's total raid healing for the entire night. What you're seeing is that I did 17% of the total raid's healing and that my nearest competition is a full 1.5 million behind me in healing.
The sad part? I thought I was doing a horrible job last night. As a caveat to those numbers, I did have a shadow priest in my group, so mana was not a huge issue. No matter how well I performed, there are plenty of things to work on. Most notably, I have a real issue remembering to blow Bloodlust on my own. I have to learn to do that without being told. Additionally, I still need to work on my positioning. I could be doing a better job of placing myself so that more people are in range of my heals.
I did practice being more reactive in my healing like the new resto shaman, and I think the results paid off. My overheal is surprisingly low on heals that I primarily cast at full rank, like lesser healing wave and healing wave. That shows that I was healing intelligently and reacting quickly. Not quickly enough for my own tastes, but the numbers show that I was doing better than I thought.
On a related note, Nature's Guardian is definitely worth the five talent points and I won't be respeccing from my standard raiding build any time soon. This WWS parse proves its effectiveness, I think.