mean, stdev = calculate_stats(item["rates"])
if mean is not None:
mean = float(mean) / 1000000
- old = float(item["last_old"])
+ old = float(item["last_old"]) if item["last_old"] else None
item["mean"] = mean
item["change"] = ((round(mean, 1) - round(old, 1)) / round(old, 1))\
- * 100
+ * 100 if old else None
item["stdev"] = stdev / 1000000
# Sort the list, key = change