Our construction operations continue to perform extremely well in terms of profits, cash flow and return on capital employed. Operating income from the core lubricants business improved, reflecting stronger margins, while operating profit also increased from antifreeze and the used motor oil collection business. Operating profit from R-12 automotive refrigerant was down due to this year's cool spring, while automotive chemicals and Valvoline Instant Oil Change showed modest declines. Sales tonnage totaled 13 million tons for the quarter and 54 million tons for the year. Net income, excluding unusual items, was higher than ever before.
Lower debt means materially lower interest expense going forward.
As a result, our balance sheet is stronger in terms of our debt to capital ratio than at any time since 1988. The price of our common stock appreciated 37 percent. Our total return to shareholders, including stock price appreciation and dividends, was 40 percent, and we delivered a return on common equity of 15 percent. We merged our coal investments into a publicly traded entity. Segments formerly identified as Petroleum and SuperAmerica were combined effective October 1, 1996.