How tall will an Italian Plum tree grow?

Question:I have a dwarf Italian plum tree that we planted last year. How tall should I expect it to grow, and how much should it grow each year? I live in the Seattle area.

Answers:
Cultivar: Fellenberg (ITALIAN PLUM)
Family: Rosaceae
Size: Height: 15 ft. to 20 ft. (usually semi-dwarf)
Width: 15 ft. to 30 ft.
Plant Category: edibles, fruits, trees,
Plant Characteristics: high maintenance,
Foliage Characteristics: medium leaves, deciduous,
Foliage Color: dark green,
Flower Characteristics: fragrant,
Flower Color: whites,
Tolerances: drought, heat & humidity,

Requirements
Bloomtime Range: Mid Spring to Mid Spring
USDA Hardiness Zone: 5 to 9
AHS Heat Zone: Not defined for this plant
Light Range: Sun to Full Sun
pH Range: 4.5 to 6.5
Soil Range: Some Sand to Some Clay
Water Range: Normal to Normal
Italian prune is self-fertile and pruduces freestone purple-skinned and yellow-fleshed plums. They are sweet and of the type suitable for drying into prunes.