In this case the translation is not Evolution, according to my interpretation.
I would use "Increases" in case the graph is going upwards year after year. If it is not so I would use Tendency or just Graphic line or Graphic representation of data. Hope it helps

1 option!

--------------------------------------------------
Note added at 16 mins (2012-08-06 19:49:38 GMT)
--------------------------------------------------

"Performance" is also possible, but I prefer "progress" over the long-term.

Meaning gradual change, common usage as a header in figures and graphics in trade journals, esp. in Europe.
Also in financial statements - "balance sheet, profit & loss account, evolution of the figures over the years.."

Following the rest of the heading and your description of what the graphic represents, I would choose a term generally used in English for this kind of graphic or table. If you Googe "supply-disposition" or "stocks" with the word "pulses" you'll generate many examples such as:

Pulse and special crop production, stocks, supply-disposition tables and publications Statistics Canada http://www.pulsecanada.com/pulse-industry/market-news

www.rayglen.com/.../mar_2011_PSC... - Formato de archivo: PDF/Adobe Acrobat
15 Mar 2011 – production and supply are forecast to decrease by 11% and 8%, ... Total carry-out stocks are expected to fall for the third consecutive year and .... CANADA: PULSES AND SPECIAL CROPS SUPPLY AND DISPOSITION ...
www.agr.gc.ca › ... › Publications - 26 Aug 2010 – However, India remains a net importer of vegoils and pulses. .... the Indian government plans to lease additional storage space to accommodate burgeoning stocks and it ... India: Grain and Oilseed * Supply and Disposition ...
Other alternatives might be stocks (which also gets hits) or warehoused stocks. www.viterra.com/.../grainstorage.../st... - Warehoused receivals may be limited if the storage units allocated for particular bin ... After growers arrange the sale of all or part of their warehoused stock to a ... cent per tonne for cereals and oilseeds, and 0.85 per cent per tonne for pulses. https://www.google.es/search?q=disposition of stocks pulses ...



--------------------------------------------------
Note added at 3 hrs (2012-08-06 22:39:01 GMT)
--------------------------------------------------

I think that the rest of the heading and the date spread is sufficient to communicate the idea of "evolución."

Spanish term (edited): Evolución

An alternative.